Overload clutch



2 sheets-sheet 1 Aug. 1, 1939. H. P. GRoHN ovERLoAD CLUTCH Filed May 31, 1938 KN EN ww SN %N NN NN NW MN 1Km. I 1 Gm. I I n I `..I.." .QN QM. LT I I+ um. MW WN wm. x QW %\1 QM.. wn.; QN Nm. l@ m@ MN mw. MVM, .mfr/ w ww .Wg

INVENToR. 72272719 Gro/Z3 ATTORNEYS.

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Patented Aug. l, 1939 UNITED STATES PATENT OFFICE 'z claims.

This invention relates to overload clutches and has for its principal object to provide an overload clutch which is adapted to operate with a predetermined load and which is adapted to automatically become disconnected when subjected to an excessive load.

One of the objects of the invention is to provide an improved overload clutch in which the clutch elements are completely separated when the device declutches on overload.

A further object of the invention is to provide scription of a preferred embodiment thereof,-

taken in conjunction with the accompanying drawings, in which:

Figure 1 is a longitudinal section through a clutch embodying my invention;

Fig. 2 is a fragmentary detail showing the manner in which the clutch is reset;

Fig. 3 is a fragmentary view corresponding to Fig. 1, showing the manner in which the clutching elements are separated on overload;

Fig. 4 is a similar view, showing the relation of the clutching elements when the clutch is open;

Fig. 5 is a face view of one of the clutching elements, being the driving clutching element;

Fig. 6 is a slmil'ar view of the other or Adriven clutching element, and

Fig. 7 is a sectional detail view, line 1'-1 of Fig. 4.

Referring to the drawings, the reference numeral II! designates the wall of a gear box or other portion of a machine which is equipped with the improved clutch. For the ease of adjustment and repair, the improved clutch is located in a tubular housing II which is threadedly mounted in a boss I2 so that the housing II is supported on the outsideof the machine. The housing II is closed at its outer end by a cap I3 which may readily be removed for adjustment and repair, and particularly for regulating the degree of overload at which the clutch automatically opens.

In this embodiment of the invention the gear taken on the or ratchet I4 may be regarded as the driving member, the driven member being the shaft I5. It will, of course, be understood that the invention is not intended to be limited to these particular driving and driven elements, since my device is capable of being applied to all kinds of machinery.

The ratchet I4 is rigidly secured to a sleeve I6 which is rotatably mounted in a suitable bushing I1 located in the boss I2. The sleeve I6 extends into the housing I I, 'as best seen in Fig. 1, and its outer end, that is, the end remote from the ratchet wheel I4, is provided with two opposite tooth portions I8, each of which occupies somewhat less than one-quarter of its circumference. One

-side I9 of each tooth I8, that is, the driving side, is cut at a slope relative to the axial direction. as best seen in Fig. 3. The angle which this slope makes with the axial direction is not critical, but it may be of the order of 30 degrees. Between the teeth I8, the sleeve I6 is provided with relatively large recesses 2U.

The complementary clutching element 2| is in the form of a sleeve mounted on the shaft I5. This element is keyed to the shaft so that it may slide longitudinally thereon while rotating with the shaft I5. The sleeve 2| is provided with an annular projection or rib 22. The face 23 of the rib, which is directed towards the sleeve I6. is preferably slightly beveled. 'I'he opposite face of the rib 22 serves as an abutment for a helical spring 24 which is located around the outer portion of the shaft I 5.

The outer end of the spring 24 rests upon a nut 25 which is threadedly mounted on the shaft I5, this nut being available for adjustment when the cap I3 is removed from the housing I I. This adjustment may be effected by a suitable wrench.

The face of the sleeve 2I which is adjacent the sleeve I6 is provided with opposite tooth portions 26 and with opposite recesses 2l which are complementary to the recesses 20 and the teeth I8. respectively. During normal driving operation the teeth IB are located in the recesses 2'I and the teeth 26 are located in the recesses 20. The teeth 26 have their surfaces 28, that is, the surfaces which are located adjacent the faces I9 of the teeth I8, sloped to the same extent, as best seen in Fig. 1. The drive is communicated from the sleeve I6 to the sleeve 2l by means of these coacting faces. `It will readily be understood that when the sleeve I6 is rotating in counter-clockwise direction, as viewed from the right in Fig. 1, the slope of the faces I9 and 28 is such that the sleeve 2I tends to move away from the sleeve I6.

This movement is effectively prevented under normal conditions by the spring 24, with the result that the sleeve 2| remains in the relative position shown in Fig. 1 and is driven by the sleeve I6.

The result of this drive is, of course, the driving of the shaft I5 upon which the sleeve 2| is keyed. When, however, the shaft I5 is overloaded, the thrust applied between the sloping surfaces I3 and 23 is sufllcient to move the sleeve 2| axially against the compressive action of the spring 24. Consequently, the outer faces of the teeth I3 come into contact with the outer faces of the teeth 26 and the drive is terminated.

Means are provided whereby the teeth 26 are prevented from dropping into the recesses 23 as the sleeve I6 continues to rotate. For this pur-A pose I slidably mount a plunger 23 in a cap 33 which is threadedly mounted in an opening in the wall of the housing II adjacent the normal location of the annular rib 22. 'I'he plunger 23 is biased inwardly by a spring 3| which bears against the interior of the cap 33 and against a bead 32 near the inner end of the plunger. At the inner extremity the plunger 23 carries a stepped projection including a frustro-conical portion 33 immediately adjacent the bead 32 and a smaller central projection 34 at the innermost end of the plunger 23. The innermost projection 34 normally bears against the surface of the annular rib 22. When the sleeve 2|, is displaced on overload in the manner described, the annular rib 22 is moved clear of the projection 34 so that the same may drop inwardly over the surface 23 thereof. It is to be noted that this relation would not maintain the two elements I6 and 2| in completely separated relation since the teeth 26 and I3 would contact as the sleeve I6 continued to rotate.

It may here be noted that the present embodiment of the invention is more particularly intended for intermittent drive, as where the ratchet |4'it driven step by step by means of a tooth or pawl (not shown). Consequently, it is preferred to provide the outer end of the shaft I5 with a square nut 3`I which'is adapted to be held by a wrench when the nut 25 is being actuated to adjust the compression of the spring 24 which, in turn, determines the degree of load at which the clutch will become disengaged.

For the same reason I provide the stepped stop members 33 and 34. Thus, if the ratchet wheel I4 is being moved one tooth at a time, then, when the shaft I5 is heldstationary by an obstruction or overload, the one-step movement of the ratchet I4 may not be sufficient to completely separate the surfaces I3 and 23 of the clutch elements. Consequently, the ratchet wheel I4 might back up and the sleeve 2| might simply move back to its originalposition. This is prevented by the stepped stop member 33, 34, because the smaller stop is arranged to engage the rib 22 and prevent ,the full return of the sleeve 2|.

During the next movement of the ratchet wheel I4, the sleeve 2I is moved to the left, as viewed in Fig. 1, until the faces 23 and 21 of the clutch elements are brought into abutting relation. The action of means which will now be described continues the displacement of the sleeve 2| to the left until the stop element 33 is enabled to move into its position as shown in Figs. 3 and 4, in which position the clutch elements are completely separated.

The complete separation of the clutch elements is eected by means of tilting dogs 33 which, as

seen in Figs. l, 3 and 4, are located in opposite recesses 35 provided in the teeth of one of the clutch elements. In the embodiment of the invention illustrated, .the recesses 35 are provided in the teeth 26 of the sleeve 2|. 'Ihe recess 35 is provided with a sloping or flaring face 33 and a face 33 which is preferably parallel to the axis of the shaft I5. Consequently, the dog 33 may move between its positions shown in Figs. 4 and 3, but it is normally biased towards the'position in Fig. 4 by means of a spring 43.

The lower end of the recess 35 is provided with lateral recesses 4| and 42 which receive lateral lugs 43 at the outer end of the dog 33. It will be noted that the recess 4|, which is adjacent the face 33 of the recess 35, is relatively large to permit the displacement of the dog 33 into its position as shown 'in Fig. 3. The dog- 33 is of suilicient length that it projects beyond the surface of the teeth 23.

When a condition of overload is reached the outer faces of the teeth 26 come into contact with the outer faces of the teeth I3. Continued rotation of the clutch member I6 brings the sloping faces I3 thereof into engagement with` the upper ends of the dogs 33. 'I'he result is that the dogs 33 are tilted into the position shown in Fig. 3 and continued rotation of the clutch member I6 causes the sloping faces I3 to ride upwardly over the tilted dogs. The result is that the sleeve 2| is displaced downwardly, as viewed in Fig. 1, to an extent which brings the sleeve 2| into its position shown in Fig. 4, that is, a position in which the sleeve 2| and the dogs 33 are completely separated from the clutch member I6. The sleeve 2| is held in that position by the stop member 33 which is caused to drop into the position shown in Figs. 3 and 4 by the spring 3|. The spring 43 causes the dog` 33 to return from its position shown in Fig. 3 to its position shown in Fig. 4.

When the obstruction or condition which caused the overload of the shaft I5 has been removed or remedied, the stop members 33 and 34 are withdrawn and the sleeve 2| is allowed to movel back to its operative position. In order to bring the teeth I3 and 26 into operative relation,

it may be necesary to hold thestop elements 33,

and 34 out for an instant. The means by which the clutch may be reset may comprise a lever 44 which is pivotally mounted on the outer end of the plunger 23. The lever 4 4 rigidly carries one or more lateral projections 45 which are adapted forcibly to engage the cap 33 when the lever is displaced towards one side.

As best seen in Fig. 1, the plunger 23 has an outward position during normal operation. When the clutch becomes completely disengaged, as shown in Fig. 4, the plunger moves-inwardly, carrying the handle 44 inwardly into the position shown in dotted lines in Fig. 2. It will readily be understood from this figure that when the lever 44 is displaced to one side, one of the projections 45 engages the cap 33 and the plunger 23 is drawn outwardly into the position shown in Fig. l. When this is done for an instant, the clutch reengages.

I prefer to provide a resilient member 46 on the lever 44, which resilient member is adaptedto v'engage the outer end of the plunger 23. Consequently, the handle 44 tends toremain in the position in which it is placed. Itfwill, however, be understood that when the sleeve 2| is moved outwardly, the plunger 23 is free to move inwardly under the action of the spring 3| so as to lock the clutch in disengaged relation. This inward movetiti dll

. the invention except in so far as set forth in ment of the plunger 29 brings the handle 44, into the dotted line position shown in Fig. 2.

Although the invention has been disclosed in connection with the specific details of a preferred embodiment thereof, it must be understood that such details 'are not intended to be limitative oi the accompanying claims.

Having thus described my invention, what l claim as new and desire to secure by Letters iPatent oi the United States is:

l. an overload clutch comprising clutch mem bers having engaging iaces in sloping relationv to the driving direction whereby excessive load tends to separate the members, resilient means tending to prevent such separation, a movable element on one oi' said members adapted to bedisplaced bythe other member to edect a further separation oi said members, means for holding said members in completely separated relation, and means ior returning said element out oi contact with said other member.

2. -iin overload clutch comprising clutch members having engaging faces in sloping relation to the driving direction whereby excessive load tends to separate the members, a dog tiltably carried by one member and adapted to be displaced by the other member after such separation whereby to eiiect a .inrther separation of said members, resilient means tending to prevent the separation oi said members, latch means ior releasably holding said members in separated relation, and spring means for returning said element to non-tilted position out oi contact with said other element.

d. iin overload clutch comprising clutch members having interengaging teeth, said teeth having sloped faces whereby excessive load tends to cause separation of the members, yielding means opposing such separation, a tilting dog in one member and projecting beyond the member ear rying it to enable it to be engaged and tilted by the other member when the members are separated, the tilting oi said dog being adapted to eiiect a further separation oi the members, means i'or holding said members completely separated and out of contact, and means lor returning said dog to non-tilted position and ont oi contact withy teeth of one member having a recess, a dog in said recess adapted for limited tilting movement therein, a spring tending to hold said dog in untilted position, said dog being adapted to project beyond the tooth in which it is located and being adapted to project to a greater degree when tilted, whereby on overload the teeth oi the sleeves are separated and a tooth of the other sleeve engages and tilts the dog to effect complete separation, and means ior holding said sleeves in completely separated relation.

5. An overload clutch comprising clutch members having engaging iaces in sloping relation to the driving direction whereby excessive load tends to separate the members, resilient means tending to prevent such separation, a movable element.

on one or said members adapted to be displaced by the other member to effect a further separation oi said members, a plunger ior holding said members in completely separated relation, and sans for returning said element out oi contact with said other member.

ii. dn overload clutch comprising clutch members having engaging faces in sloping relation to the driving direction whereby excessive load tends to separate the members, resilient means tending to prevent such separation, a movable element on one of said members adapted to be displaced by the other member to eiiect a iurther separation oi said members, a plunger' for holding said members in completely separated. relation, a lever mounted at the outer end of said plunger ior ei'- reeting withdrawal oi the plunger, and means ior returning said element out oi contact with said other member.

"7. iin overload clutch comprising a pair oi" sleeve-Millie clutch members adapted to abut, the abutting ends being provided with interengaging teeth, a spring iorcing one member into engagement with the other member, adjacent iaces oi said teeth being sloped relative to the atrial di rection oi the members, a movableelement ear-I ried by one oi said teeth and normally projecting beyond the tooth carrying it and being yadapted to be tilted so as to increase the degree 'oi its projection relative to the tooth carrg it, and means ier returning the element to nontilted position, whereby the teeth separate on overload and the projecting element is tilted by the other member to increase the separation thereoi, and a latch arranged to hold said members in a state ci maximum separadon.

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